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Re: coupling

Bob,
When I first setup my coil, I had the secondary in line
with the primary (flat style). I had a problem with
racing sparks down the secondary. I elevated the
secondary a little over an inch and the racing sparks
down the secondary stopped. Raizing the secondary
loosened or reduced the coupling (opposite of your
thoughts posted). I was able to achieve the maximum
amount of coupling (without racing sparks down the
secondary) by using this technique. It is possible that
you might be able to tighten your coupling a bit if your
are not having racing sparks down the secondary or
primary to secondary arc-overs. If you do tighten up the
distance between the two windings, raising the secondary
in small increments (1/4") can get you to the "best
coupling" distance (my opinion).
Bart

Tesla List wrote:
> 
> Original Poster: bob golding <yubba-at-clara-dot-net>
> 
> Hi All,
> 
>         Have just been playing around with the coupling of my coil.
> 9 Kv 60mA neon,
> Conical 30 degree primary 9 turns 3/8" Cu,
> home made flat plate cap 15 nF,
> RQ gap 0.125" gap, vacuum quenced
> 41/2" secondary 21" winding length, About 980 turns 23 AWG,
> 19" x 4" toroid.
> 
> I am getting 20" sparks to a grounded rod with the primary tapped at 8 1/2
> turns. I started with the base of the secondary windings about 2" above the
> first turn of the primary. This gave 20" sparks. I then moved the secondary
> down to be in line with the first turn of the primary. This does not seem
> to have made any differance to the spark length. is this because the coil
> is too far out of tune? I did notice that safety gap activity is less with
> the secondary lower. Am I right in thinking that the coupling is at the
> mininim when the the secondary is in line with the bottom turn of the
> primary, therefore there is no point in adjusting the coupling below this
> point?, and  that coupling is increased as the secondary is raised. How
> much differance does the distance between the the primary and the secondary
> make?. At the moment I have about 1" I would find it hard to tighten this
> up due to the design of my coil.
> 
> many thanks
> 
> bob golding lightning without rain
> 
> bob yubba.clara-dot-net